A verb glossed “plant, grow” in notes on Words, Phrases and Passages from the Lord of the Rings from the late 1950s or early 1960s discussing the derivation of S. galenas “pipeweed” (PE17/100). The verb ala- was used several times in verb charts, such as illustrating pronominal suffixes (PE17/132) or giving the inflections of a-verbs (PE22/164).
Conceptual Development: As suggested by Gilson, Welden and Hostetter, the earliest appearance of this verb might be in the phrase ᴱQ. alildon ornin lassevarnen, which seems to mean something like “✱grow trees leaf-brown” (PE16/80). The word element (and verb?) ᴹQ. ’al appeared under the root ᴹ√GALA “thrive” in The Etymologies of the 1930s (Ety/GALA); an earlier iteration of this root had the glosses “grow, thrive, prosper, be healthy, be glad” along with a word element (and verb?) al-, but the gloss “grow” was deleted along with a statement that “grow is ol-” (Ety/GAL(AS)).
Indeed, the verb ᴹQ. ’alā- “grow” appeared in Quendian & Common Eldarin Verbal Structure (EVS1: PE22/98) from the late 1940s and again in Quenya Verbal System from 1948 (QVS: PE22/106 note #39), but in the latter document it was replaced by ᴹQ. ola- “grow” (PE22/113 note #80). However, in Common Eldarin: Verb Structure (EVS2) from the early 1950s, primitive ✶galā- was restored, but with a more specific sense “grow (of plants)”, as opposed to ✶olā- “become, come into being, turn into (another state)” (PE22/134). This plant-growth meaning seems to have carried forward into Tolkien’s later writings (see above: PE17/100).
Neo-Quenya: For purpose of Neo-Quenya, I would assume the verb ala- only means “grow” when applied to plants, but more generally could mean “✱thrive, flourish” when applied to other living creatures, as in i lótë ala “the flower grows” but i Elda ala “the Elf thrives/flourishes”. Based on its glosses from PE17/100, I would assume it can also be used transitively when applied to plants to mean “cause to grow = plant”, as in i Elda ala lóti “the Elf grows/plants flowers” or álëa lóti “... is planting flowers”.
One of the Ithryn Luin (Blue Wizards) who went to the East and South (UT/394). The meaning of his name is unclear, though the final element seems to be -tar “-lord” as seen in other names like Annatar and Sorontar. Damien Bador suggested that it might be related to ✶alatā “radiance” (variant form of ✶ñ(g)alatā) or a restoration of [ᴱQ.] alatya- “to protect”, analogous to his other name Rómestámo “East-helper”.